Samsung seems to always have great phones out. My current T-Mobile contract ends this upcoming August or September, so depending what phones are available for me to pick from, most likely there'll be a nice Samsung somewhere in the bunch. Hopefully this one included^

I'm thinking of buying a 4S for my mom as a birthday gift. I'll probably get the white one. I've read there are some differences in picture quality between the white and the black model, is this true?

Do not think so. I currently have black iPhone 4 and it takes picture fine. (Except in fluorescent lighting, there'll be a green blob). Your mom will LOVE the iPhone 4S, here are a few sample pictures from what I took on my iPhone 4 (takes best pictures under direct sunlight).

My airplane ride with a buddy who needed to complete a 5 hour+ flight.

Edit: Just found an example of green blob

It's been explained many times. It's the relationship between the flickering fluorescent lights and the slow electronic shutter. Basically the lighting and white balance are not consistent during the exposure.

Similar problems can be shown on any camera. With a more sophisticated camera you can avoid the problem with a higher shutter speed, change in ISO, lighting etc. With a simple camera you can only change the lighting, location etc.